Cole has appeared in numerous films and TV shows, beginning in 1961 with a role in the film drama, Forbid Them Not. Other film credits include the role of Mark in the 1966 science fiction film, The Bubble, later re-titled Fantastic Invasion of Planet Earth, Spivey in the western Chuka (1967), Alan Miller in The Last Child (1971), which was nominated for a Golden Globe Award,[1] and as Cliff Norris in Beg, Borrow or Steal (1973). He did a great deal of stage work after The Mod Squad went off the air, such as Cat On A Hot Tin Roof.

But it was his role as Pete Cochrane, a troubled youth turned crime fighter in The Mod Squad (1968–1973), that made Cole an international celebrity. Cole's boyish good looks and brooding, deep-voiced personality meshed perfectly with his character's backstory—a ne'er-do-well son of wealthy parents who had evicted him from their home after he had stolen a car.[2] Produced by Aaron Spelling and Danny Thomas, The Mod Squad resonated with counterculture-era viewers and ran for five seasons, during which a total of 123 episodes were produced.[3]

According to TVGuide.com, Cole originally balked at the part of Peter Cochran when he realized he would be playing an undercovercop, saying, "I'm not going to take the part of a guy who finks on his friends!" He changed his mind, however, when he read the script and gathered the show's potential appeal.

Cole is also known for an incident in 1973 which was broadcast live on Australian television during the annual TV WeekLogie awards. Stepping on stage to accept an award, Cole – described in subsequent news articles as either drunk or "in a tired and emotional state"[4] – gave a barely coherent "thank you" speech that ended with the actor saying, "Oh, shit."[5] This was the first time this profanity had been heard on Australian television.[6]

Cole went through treatment in the Betty Ford Clinic in the early 1990s to get his drinking problem under control.[7]

Cole continues to act in various film and television projects, and played the character Charles Hadley in a 2006 episode of the NBC television series ER. Cole most recently made an appearance in the 2007 thriller Mr. Brooks as the attorney for Demi Moore's character of Detective Tracy Atwood.